foo.cc: In function 'void x(std::string&)':
foo.cc:4:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
    4 |  for(int i=0;i<a.size();i++)
      |              ~^~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:14:6: error: could not convert 'a.std::__cxx11::basic_string<char>::operator=(b)' from 'std::__cxx11::basic_string<char>' to 'bool'
   14 |  if(a=b)
      |     ~^~
      |      |
      |      std::__cxx11::basic_string<char>

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